Heretofore, building panels having thermal insulation of plastic foam and a facing layer of vinyl plastic mechanically bonded to the plastic foam, as exemplified in the U.S. Pat. No. 4,034,528 to Sanders et al, have not proven to be satisfactory in use as exterior siding. A disadvantage of this type of building panel is that the thin facing layer of vinyl chloride, or other similar thermoplastic, readily expands under ambient heating and warps and wrinkles because it is only mechanically bonded to a rigid plastic foam layer having a highly different coefficient of expansion. This warping and wrinkling of the facing layer, while undesirable in and of itself, also results in the bond between the facing layer and the foam insulation being broken which, in turn, results in voids through which moisture can penetrate the building panel. Since the expanded foam insulation and similarly described plastic foams are highly susceptable to absorption of moisture, the moisture entering the voids is readily absorbed by the foam insulation and passes from the foam insulation via those voids as changes in ambient weather conditions occur. This resultant cyclical and rapid absorption and loss of moisture over a wide range of conditions normally encountered under ambient environmental conditions causes structural deterioration of the foam insulation because of its dimensional changes, especially in the lateral direction, diminuation of its insulating capability and potential rotting of the wood support structure on which the panels are mounted. The building panel of this invention overcomes the aforesaid shortcomings of the heretofore known building panels of vinyl and thermally insulated type.
It is therefore an object of this invention to provide a building panel for exterior use which has a relatively long operative life during which thermal insulation and resistance to moisture penetration is optimal.
Another object of the present invention is to provide a building panel for exterior use of laminated construction, having a thermal insulating layer and a plastic outer weather resistant layer, in which deformation of the building panel is obviated.
Another object of this invention is to provide a building panel for exterior use of laminated construction having a thermal insulating layer and an outer layer of plastic, which is relatively stiff and having dimensional integrity under a wide range of ambient weather conditions.
A further object of the present invention is to provide a building panel for exterior use of laminated construction, having a lamination of foam insulation material, in which any cyclical absorption and release of moisture by the foam insulation under fluctuating ambient weather conditions of temperature and humidity is substantially negated.
A still further object of this invention is to provide a method of fabricating a building panel for exterior use of laminated construction, having a layer of thermal insulation and a plastic outer weather resistant layer, in which building panel the structural integrity of the plastic outer layer is maintained and moisture penetration is minimize throughout the operative life of the building panel.